NITROGEN CARRY-OVER IMPACTS IN IRRIGATED COTTON PRODUCTION, SOUTHERN HIGH PLAINS OF TEXAS

A dynamic optimization model which introduces an intertemporal nitrate-nitrogen residual function is used to derive and evaluate nitrogen fertilizer optimal decision rules for irrigated cotton production in the Southern High Plains of Texas. Results indicate that optimal nitrogen applications critically depend on initial nitrate-nitrogen levels and nitrogen-to-cotton price ratios. Also, the results indicate that single-year optimization leads to suboptimal nitrogen applications, which helps explain long-term cotton yield declines in the Southern High Plains of Texas; but single-year optimization does not significantly impact the net present value of returns of irrigated cotton operations.Crop Production/Industries,

SOCIAL WELFARE AND ENVIRONMENTAL DEGRADATION IN AGRICULTURE: THE CASE OF ECUADOR

A non-linear optimization model which maximizes total Ecuadorian social welfare, defined as the sum of consumers' and producers' surpluses for the four major crops (corn, bananas, rice and African palm) is developed to evaluate the tradeoff between welfare and environmental degradation in Ecuador. It was found that a total welfare loss of US$122 million (a 11 percent reduction - from US$ 1.112 billion to US$ 989.66 million) would be expected from a 30 percent reduction in the total pesticide load on the environment in the production of the four major crops. The distributional impacts of the welfare loss were found, however, to be significantly skewed toward the loss of consumers' surplus. Specifically, a 30 percent reduction of total pesticide load on the environment would result in a reduction of 3.86 percent of producers' total surplus while consumers would be expected to loose 19.46 percent of their total surplus.welfare tradeoff, environmental impacts, non-linear optimization, Environmental Economics and Policy,

Comparación de métodos de muestreo para estimar la población del gorgojo del pimiento

Five sampling methods were evaluated simultaneously for their efficiency in estimating pepper weevil (Anthonomus eugenii Cano) populations. The use of yellow sticky traps was assessed superior to other methods when correlated with direct weevil counts. Comparison between sticky traps of eight different colors indicated that yellow and white traps are significantly more attractive to pepper weevils than light green, red, dark green, gray, blue or black. Commercially available Pherocon AM traps were tested for efficiency. Weevil catch in these traps was positively correlated with population density, but relationship was weak and weekly catch erratic. Factors affecting trap efficiency are mentioned.Una evaluación de cinco métodos de muestreo indicó la superioridad de trampas pegajosas amarillas en la estimación de los niveles de densidad del picudo del pimiento, Anthonomus eugenii Cano. Una comparación entre trampas pegajosas en ocho colores resultó en la determinación de que los colores amarillo y blanco atraen significativamente más adultos que otros colores. Además, se evaluó la utilidad y eficacia de las trampas comerciales Pherocon AM. Se encontró que la captura en éstas podía correlacionarse con los niveles de densidad del picudo del pimiento observados en el campo. Sin embargo, esta correlación resultó débil y errática debido en la mayoría de los casos a deficiencias en su diseño, con respecto a este picudo y su hábitat

THE CYCAD SCALE, AULACASPIS YASUMATSUI TAKAGI (HOMOPTERA: DIASPIDIDAE): A NEW INVASIVE PEST TO PUERTO RICO

THE CYCAD SCALE, AULACASPIS YASUMATSUI TAKAGI (HOMOPTERA: DIASPIDIDAE): A NEW INVASIVE PEST TO PUERTO RIC

PARATACHARDINA PSEUDOLOBATA (HEMIPTERA: COCCOIDEA: KERRIIDAE): A NEW INVASIVE SCALE INSECT IN PUERTO RICO

PARATACHARDINA PSEUDOLOBATA (HEMIPTERA: COCCOIDEA: KERRIIDAE): A NEW INVASIVE SCALE INSECT IN PUERTO RIC

Dynamic regression model for hourly river level forecasting under risk situations: An application to the Ebro River

This work proposes a new statistical modelling approach to forecast the hourly river level at a gauging station, under potential flood risk situations and over a medium-term prediction horizon (around three days). For that aim we introduce a new model, the switching regression model with ARMA errors, which takes into account the serial correlation structure of the hourly level series, and the changing time delay between them. A whole modelling approach is developed, including a two-step estimation, which improves the medium-term prediction performance of the model, and uncertainty measures of the predictions. The proposed model not only provides predictions for longer periods than other statistical models, but also helps to understand the physics of the river, by characterizing the relationship between the river level in a gauging station and its influential factors. This approach is applied to forecast the Ebro River level at Zaragoza (Spain), using as input the series at Tudela. The approach has shown to be useful and the resulting model provides satisfactory hourly predictions, which can be fast and easily updated, together with their confidence intervals. The fitted model outperforms the predictions from other statistical and numerical models, specially in long prediction horizons

Agroterrorism: Options in Congress

Although U.S. intelligence agencies have not identified any terrorist acts targeting agricultural production (i.e., agroterrorism) in the United States to date, the events of September 11, 2001 have awakened the nation to their possibility. Some experts estimate that a single agroterrorist attack using a highly contagious livestock disease could cost between $10 billion and$30 billion to the U.S. economy. This report examines the potential threats to America’s agriculture from a deliberate biological attack, describes the current defense structure and capabilities available to respond to agroterrorism, and analyzes current congressional proposals to address the threat of biological weapons to U.S. agriculture